Dead bed protective sleeve for use in processing taconite

ABSTRACT

To minimize the amount of wear at the outlet or discharge pipe in the bottom of a tank or box through which a liquid or slurry containing abrasive particles flows, such as in the processing of taconite, a dead bed protective sleeve of a material having abrasion-resistant properties is employed, the sleeve having a flange that overlies the bottom of the box circumjacent the outlet pipe and also having a cylindrical portion depending downwardly into the outlet pipe. The flange functions as a dam or baffle so that the particles build up therearound to provide a cushioning effect which protects the bottom of the box in this region. The joint where the outlet pipe is connected to the box is also protected. Still further, the upper portion of the outlet pipe where turbulent action occurs is protected by the depending cylindrical portion of my sleeve.

United States Patent 91 Rowell [4 1 Feb. 5, 1974 1 DEAD BED PROTECTIVE SLEEVE FOR USE IN PROCESSING TACONITE [75] Inventor:

[73] Assignee: I. R. A., Incorporated, Hibbing,

Minn.

22 Filed: Jan.24, 1972 21 Appl.No.:219,943

Byron G. Rowell, Virginia, Minn.

[52] US. Cl. 137/590, 209/494 [51] Int. Cl B03b 11/00 [58] Field of Search... 137/590, 592, 602, 262, 263, 137/265, 266, 375, 582; 138/96, 110, 140',

Primary Examiner-William R. Cline Attorney, Agent, or Firm-Stuart R. Peterson [5 7] ABSTRACT To minimize the amount of wear at the outlet or discharge pipe in the bottom of a tank or box through which a liquid or slurry containing abrasive particles flows, such as in the processing of taconite, a dead bed protective sleeve of a material having abrasionresistant properties is employed, the sleeve having a flange that overlies the bottom of the box circumjacent the outlet pipe and also having a cylindrical portion depending downwardly into the outlet pipe. The flange functions as a dam or baffle so that the particles build up therearound to provide a cushioning effect which protects the bottom of the box in this region. The joint where the outlet pipe is connected to the box is also protected. Still further, the upper portion of the outlet pipe where turbulent action occurs is protected by the depending cylindrical portion of my sleeve.

10 Claims, 3 Drawing Figures PAIENIEU 74 SIIEEI 1 OF 2 STORAGE /Z /0 /4 4 I ROD MILL /6' /6 r MAGNETIC MAGNETIC MAGNETIC 22a SEPARATDR SEPARATOR SEPARATOR I L 20 b 20/ 22a 20 22a, I

Z26 1 22b I COLLECTION BOX COLLECTION BOX 306 r 243!) BALL MILL 32 42 3 \w/fl' PUMP a SUMP 304 CYCLONE 4 I 44 I- 24 a HYDRO- 46 SEPARATOR I I 48 COLLECTION BOX 46/ 50 MAGNETIC MAGNETIC MAGNETIC 22% 30C SEPARATOR SEPARATOR SEPARATOR r 22d 50/ 50 L 22 ZZe COLLECTION .BOX

COLLECTION BOX TO TAILINGS DISPOSAL SITE DEAD BED PROTECTIVE SLEEVE FOR USE IN PROCESSING TACONITE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to the processing of taconite, and pertains more particularly to a dead bed protective sleeve to be used at the outlets of the various collection and distribution boxes normally employed in the processing of taconite.

2. Description of the Prior Art Mining operations have resorted to dead bedding in designing those launders, slurry tanks and the like which are subjected to abrasive wear concentrated on only the bottom surface. The traditional approach has been to fabricate the equipment with the outlet or dis charge pipe extending a certain distance upwardly into the launder or collection box, thereby creating a dam around which the solids and the slurry will be trapped until the level of the solids is as high as the raised edge of the outlet pipe. In this manner, the slurry entering and leaving the tank or box comes in direct contact with the dead bed layer of solids instead of the tank bottom but still contacts the discharge pipe. The outlet or discharge pipe, therefore, becomes the weak point of the system since rapid abrasive wear can occur at its exposed upper edge and downwardly therein to the extent that turbulence remains a factor. As the pipe wears, the dead bed level drops until such time as it is no longer effective. When this occurs, the tank or box must be removed from service, the discharge pipe removed, and the pipe replaced. This repair, which necessitates cutting and welding, is quite costly. Of even greater significance, however, is the down time and the production lost as a result thereof.

SUMMARY OF THE INVENTION Accordingly, one important object of the present invention is to minimize the damage caused by the abrasive action of the taconite ore, both as to tailings and concentrate, as it passes through the various collection boxes located at spaced points in the processing system. More specifically, the invention has for an aim the provision of a protective sleeve having a flange and a cylindrical portion, the flange extending sufficiently above the bottom wall of the collection box so that some of the ore accumulates around each outlet having a sleeve associated therewith, thereby providing a cushioning effect for the additional incoming material, while the cylindrical portion protects the pipe itself from the swirling or turbulent action that takes place in the upper portion thereof.

Another object is to maintain the dead bed level at a substantially uniform height. In this regard, it will be appreciated that heretofore when the upper edge of the outlet pipe wears, the dead bed level drops accordingly until such time that the pipe has been eroded until it has become flush with the bottom of the tank or box. It is within the contemplation of the present invention to utilize a flange integral with the protective sleeve that resists the abrasive action and which retains its initial height so that the dead bed level is maintained at the height of the flange.

Another object of the invention is to obviate the need for having the outlet or discharge pipe extend upwardly from the bottom of the tank or box. Stated somewhat differently, the outlet or discharge pipe, when practicing the teachings of the present invention, can be welded flush with respect to the tank bottom. Also, it is within the contemplation of the invention to utilize the protective sleeve as a sealing accessory, thereby reducing the need for an absolutely liquid-tight joint.

A further object of the invention is to provide a lightweight protective sleeve for collection boxes that can be inexpensively manufactured, readily installed and easily replaced when necessary. It is planned that my protective sleeve will fit snugly into the outlet or discharge pipe, being readily installed by hand, and later manually pulled out when it is to be replaced. No fasteners or tools are required during its installation or removal.

Yet another object of the invention is to provide a protective medium for preventing or minimizing wear which utilizes the product itself. In this regard, it is to be recognized that as the particulate material contained in the slurry and deposited around the flange of my protective sleeve wears, the very product or material which wears is continually replaced. While there will be some wear over a period of time of the protective sleeve, it will be apparent that for the most part there is no comtamination owing to the fact that the material that experiences the most wear is the material itself.

Briefly, the invention envisages a polyurethane protective sleeve of unitary construction. The sleeves flange is of sufficient diameter so that it prevents the downward movement of the sleeve in the direction of material flow and is of sufficient height for the particle size that it also functions as a baffle or dam, thereby causing the particulate material to build up on the bottom of the collection box to provide protective action by reason of the cushioning effect that is derived. The sleeve has an integral cylindrical portion that extends into the outlet or discharge pipe to a sufficient depth so as to protect the side walls of the pipe with respect to the turbulent or swirling action that prevails in the upper portion of the pipe. In other words, the depth or length of the cylindrical portion is such that by the time the material has passed beneath the sleeve the flow is relatively laminar with a concomitant lessening of the abrasion action that would otherwise occur along the upper portion of the pipe. The sleeve can be readily installed and subsequently extracted from the outlet or discharge pipe whenever it is required to do so, because only a snug fit is needed. By reason of the protective sleeve, most of the abrasive wear is with respect to the taconite ore itself and very little of the material of which the sleeve is constituted enters into the flow stream. Therefore, the sleeve will have especial utility where contamination may be an important factor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow diagram in block form illustrating a typical concentrator plant in which my protective sleeve will find especial utility;

FIG. 2 is a perspective view of one of the collection boxes appearing in FIG. 1, and 7 FIG. 3 is a sectional view taken in the direction of line 33 of FIG. 2 for the purpose of showing to better advantage the construction of my protective sleeve and the relationship thereof with one of the box outlets.

. bEscRlfirioN OF THE PREFERRED EMBODIMENT Owing to the wear problems that have plagued the taconite industry for a number of years, it will be helpful in appreciating the benefits to be derived from a practicing of my invention to consider a portion of a typical taconite plant. Accordingly, an exemplary concentrator has been designated in its entirety in FIG. 1 by the reference numeral 10, although the invention will find application in agglomerators, too. Inasmuch as the mechanical construction of the component parts of the plant are generally well known, the plant need be only presented in block form.

First, attention is called to a storage bin 12. The storage bin 12, which contains ore having a particle size on the order of 4 inch or so, has a belt conveyor 14 connecting it with a rod mill 16 where the partially crushed taconite is further reduced in size by the action of the rods. From the rod mill 16, the crushed ore, now of a size such that 75 to 80 percent passes through a mesh screen, is conveyed by pipe lines 18 to several magnetic separators 20.

After separation from the concentrate (and middlings) the tailings are drawn from the separators 20 through discharge lines 22a leading to a first collection box 24a. The tailings, as is well known, contain mostly impurities and very little iron ore, thereby making it uneconomical to further use these tailings. As the description progresses, it will become apparent that the tailings collected in the box 240 are forwarded through additional collection boxes to a tailings disposal site. For the time being, though, it will suffice to point out that there is an outlet or discharge pipe a leading from the collection box 24a. I

From the several magnetic separators 20 the concentrate (and middlings of lesser iron content) is delivered or fed by way of a'conveying pipe line 22b to a collection box 24b which collects the material from the separators 20 and then discharges it by way of an outlet or discharge pipe 30b to a ball mill 32. The ball mill 32 further reduces the size of the ore and the particles thus reduced in size are fed by way of an additional pipe line 34 to a pump and sump denoted by the numeral 36.. It is from the pump and sump 36 that the so-called pulp is fed by a pipe line 38 to a cyclone separator 40.

A first pipe line 42 extends from the cyclone separator back to the collection box 24b, carrying the oversize particles upstream for a repeated pass through the ball mill 32. The concentrate, on the other hand, from the cyclone 40 is delivered by way of a pipe line 44 to a hydroseparator 46.

The tailings from the hydroseparator 46 are fed through a pipe line 220 to a collection box labeled 240. [t is this collection box 24c that receives the tailings collected from the earlier-mentioned box 24a. Actually, the collection boxes 24a and 24e, as well as the collection box 24b, can be of identical construction. It is only the number of inlets thereto in each instance that may vary, and actually the number has been shown as. different in connection with each box 24a, 24b and 240. Inasmuch as the collection boxes 24a, 24b and 24c are of identical construction, or at least of similar construction, they will be described in greater detail hereinafter; at the moment, it perhaps will be of some help to'explain that one such box has been pictured in FIG. 2, bearing the reference designation.24.

From the hydroseparator 46, the concentrate is transferred through several pipe lines 48 to additional magnetic separators 50, where further classification is made. The tailings from the magnetic separator 50 are fed by way of pipe lines 22d to still another collection box 24d. In the exemplary concentrator 10 that has been illustrated, the collection box 24d constitutes the final collection point as far as the tailings are concerned. In this regard, an outlet or discharge pipe 30d connects to a suitable conveyor that leads to a tailings disposal site that need not be referred to in detail. On the other hand, the fines or concentrate from the magnetic separators 50 are delivered via pipe lines 22e to a final collection box 24e for the concentrate. It is from the collection box 24e, more specifically through the agency of its outlet or discharge pipe 30e, that the collected concentrate is transmitted to an agglomeration pump sump. While the foregoing description has dealt with a typical or exemplary concentrator, it will be appreciated by those familiar with taconite processing that similar collection boxes 24 are employed in the agglomerator ofa taconite plant. It is in the agglomerator that the final concentrate is pelletized.

Having illustrated the foregoing information in block form, attention is now directed specifically to FIG. 2 where a typical collection box 24 has been illustrated. Describing the box 24 in sufficient detail so that a better appreciation of the invention will be had, it is to be discerned that the box 24 has a bottom wall 60, actually being flat in the illustrated case, and also has upstanding side walls 62, 64, 66 and 68. For the sake of simplification, the various lines 22 shown in FIG. 2 have been pictured as constituting chutes, but it will be understood that they normally constitute conduits or pipes which convey the pulp from location to location and which have been referred to as pipe lines with distinguishing letter suffixes when describing FIG. 1. In the depicted instance, three inlets 22 have been shown in FIG. 2, these inlets corresponding in effect to the pipe lines 22a or 22e in FIG. 1 inasmuch as the collection box 24a has three such lines 22a leading thereinto and the collection box 24e has three lines 22e leading thereinto. As far as FIG. 2 is concerned, the outlet carries the designation 30 and as can be perceived fromthe one appearing in FIG. 3 constitutes a cylindrical discharge pipe that is welded at to the edge of a circular opening formed in the bottom well 60. It will be appreciated that the upper edge of the pipe 30 does not project above the bottom wall 60. The present invention enables such a simplified joint to be utilized.

At this stage of the description, it will be well to emphasize that both the outlet pipe 30 and the bottom wall 60 are of mild steel, usually on the order of A inch thick. Consequently, both the pipe 30 and the wall 60 are exceedingly vulnerable to wear from the abrasive action of the concentrate being collected in the box 24 and discharged therefrom by way of the outlet or discharge pipe 30. As can be seen from FIGS. 2 and 3, the outlet pipe 30 has associated therewith a dead bed protective sleeve designated generally by the reference numeral 72. The one-piece sleeve 72 includes a flange 74 and an integral tubular portion 76 that projects downwardly into the outlet pipe 30, there being a bore 80 of uniform diameter extending completely therethrough;

While my protective sleeves 72 have been used in conjunction with various pipe sizes, reference will be made to a six inch pipe which is one commonly encountered size. Accordingly, the preferred outside diameter of flange 74 in this instance is eight inches, the flange having a one and one-half inch thickness or height, a height sufficient in relation to the size of ore particles to provide an adequate building up of material. Inasmuch as it is highly desirable to have only a snug fit, the outside diameter of the tubular portion 76 under these circumstances is 6.06 inches and the wall thickness of the tubular portion A inch. In order to give adequate protection sufficiently downwardly into the outlet pipe 30, the length of the tubular portion 76 was made eight inches, a length that is sufficient so that the lower edge is where the flow has become laminar. Hence, the overall length of the sleeve 72 was 9 /2 inches.

As already explained, the 1 /2 inch thickness or height of the flange 74 enables a sufficient amount of taconite to build up around the periphery of the flange and even withstands direct impingement of the abrasive particles thereon which may range in size between 8 and 300 mesh. In FIG. 3, some of the partially concentrated ore that has been built up has been labeled 82 and additional taconite flows downwardly through the sleeve 72, the latter material having been given the reference numeral 84.

It is important that the material selected for the protective sleeve 72 be highly resistant to abrasion. Polyurethane has been found satisfactory, but various elastomeric materials may be used. Actually, while urethane is normally thought to be a plastic, it possesses considerable elasticity and is sometimes referred to as being elastomeric. Consequently, the term elastomeric is intended to embrace not only urethane and other plastic materials having the appropriate physical characteristics but is also intended to include various elastomers such as neoprene. The compressibility of the material is taken into account as far as determining the amount of snug fit, that is the oversize of the cylindrical portion 76 relative to the bore of the particular pipe 30.

It has previously been mentioned that the outlet or discharge pipe 30 has been welded to the bottom wall 60 of the box 24 at 70. From FIG. 3 it will be observed that the upper end of the pipe 30 is flush or coplanar with the upper surface of the bottom wall 60. There is a distinct advantage to be gained by practicing the present invention, for heretofore it was customary to have the upper end of the pipe 30 project beyond the upper surface of the bottom wall 60 in order to form a lip or raised edge. The flow of the abrasive particles constituting the taconite 82 and 84 would abrade the upwardly directed lip formed by the pipe 30. Not only would the lip wear away relatively rapidly but also this would happen to portions of the pipes walls. Without the lip or upwardly projecting pipe portion, the cushioning effect would be lost in that there would be no dam or baffle to keep the particles from spilling into the pipe. Then, the bottom wall 60 would become exposed and subject to appreciable wear.

Accordingly, it should be evident that frequent replacements of the pipe 30 were needed in the past. If

' the bottom wall 60 had not worn too severely, then only a new outlet pipe along with a new weld 70 would be necessary. Even this required a shut down (or a bypassing) of the particular box 24. In any event, repeated replacements of the outlet or discharge pipes, suchas the pipe 30, have proved quite costly. Coupled with the still rather frequent replacement of the bottom wall 60 also, it should be appreciated that along with the labor costs incurred from such replacements plus the down time loss contributed tremendously to maintenance expenses.

However, the present invention permits the mounting of the outlet or discharge pipes 30 so that the upper ends thereof are flush with the upper surface of the bottom wall 60. Owing to the protective action afforded by the flange 74 which overlies the joint at and the marginal portion of the bottom wall 60, plus the additional protection provided to the interior of the pipe 30, the intervals without maintenance attention have been appreciably lengthened. As a matter of fact, the amount of maintenance work is now virtually insignificant in contrast to the amount of labor heretofore required. In addition, the sleeve 72 helps in sealing around the joint at 70 should the weld not be completely liquid-tight.

Even when it is necessary to replace a given protective sleeve 72, the operation is simple: all that need be done is to retract the sleeve 72 by pulling upwardly, the snug fit relationship permitting this to be readily accomplished. Only one man is required. Then, a new sleeve 72 can be present downwardly and this can be done, as should be evident, very quickly. However, it is the infrequency of sleeve replacements that contributes tremendously to the operational savings obtainable when practicing my invention.

I claim:

I. In combination, a collection box for receiving a liquid carrying therewith a particulate material having abrasive characteristics, the box including a bottom wall and side walls, said bottom wall having an outlet opening, a cylindrical discharge pipe extending downwardly from said oulet opening, and a protective sleeve of unitary construction comprising an upstanding flange overlying a marginal section of said bottom wall adjacent said outlet opening and having a cylindrical portion projecting downwardly through said outlet opening into said discharge pipe, the outer diameter of said cylindrical sleeve portion corresponding generally to the inner diameter of said pipe, said upstanding flange having a vertical height sufficient to provide a baffle for some of the particulate material, whereby the building up of particulate material around said flange further contributes to the protection provided by said sleeve.

2. The combination set forth in claim 1 in which said flange is circular.

3. The combination set forth in claim 2 in which said sleeve is of an elastomeric material.

4. The combination set forth in claim 3 in which said elastomeric material includes urethane.

5. The combination set forth inclaim l in which said sleeve is of a resilient material.

6. In a taconite processing plant, a plurality of collection boxes located at various stages in the processing plant, each box having a bottom wall and upstanding side walls, a plurality of inlet lines and an outlet line associated with each box for feeding taconite ore material thereinto and for discharging said material, respectively, said inlet lines entering through said side walls at different angles so that said material is fed into each box in different directions and said outlet line extending generally vertically from said bottom wall, said outlet line including a discharge pipe fixedly secured at its upper end to said bottom wall and coplanar therewith, and a protective sleeve having a horizontal flange overlying the upper end of said pipe and the adjacent marsaid flange has a height greater than the particle size of the taconite passing therethrough.

9. A processing plant as set forth in claim 8 in which said flange has a height greater than its radial length and said cylindrical portion has a radial thickness less than the radial length of said flange.

10. A processing plant as set forth in claim 9 in which each sleeve has a bore extending therethrough of generally uniform diameter. 

1. In combination, a collection box for receiving a liquid carrying therewith a particulate material having abrasive characteristics, the box including a bottom wall and side walls, said bottom wall having an outlet opening, a cylindrical discharge pipe extending downwardly from said outlet opening, and a protective sleeve of unitary construction comprising an upstanding flange overlying a marginal section of said bottom wall adjacent said outlet opening and having a cylindrical portion projecting downwardly through said outlet opening into said discharge pipe, the outer diameter of said cylindrical sleeve portion corresponding generally to the inner diameter of said pipe, said upstanding flange having a vertical height sufficient to provide a baffle for some of the particulate material, whereby the building up of particulate material around said flange further contributes to the protection provided by said sleeve.
 2. The combination set forth in claim 1 in which said flange is circular.
 3. The combination set forth in claim 2 in which said sleeve is of an elastomeric material.
 4. The combination set forth in claim 3 in which said elastomeric material includes urethane.
 5. The combination set forth in claim 1 in which said sleeve is of a resilient material.
 6. In a taconite processing plant, a plurality of collection boxes located at various stages in the processing plant, each box having a bottom wall and upstanding side walls, a plurality of inlet lines and an outlet line associated with each box for feeding taconite ore material thereinto and for discharging said material, respectively, said inlet lines entering through said side walls at different angles so that said material is fed into each box in different directions and said outlet line extending generally vertically from said bottom wall, said outlet line including a discharge pipe fixedly secured at its upper end to said bottom wall and coplanar therewith, and a protective sleeve having a horizontal flange overlying the upper end of said pipe and the adjacent marginal portions of the bottom wall, said sleeve further including a cylindrical portion depending downwardly into the discharge pipe.
 7. A processing plant as set forth in claim 6 in which said sleeve is of an elastomeric material and said cylindrical portion has an outer diameter slightly greater than the inside diameter of the pipe in which it is inserted, whereby said cylindrical portion has a snug fit relationship with said pipe.
 8. A processing plant as set forth in claim 7 in which said flange has a height greater than the particle size of the taconite passing therethrough.
 9. A processing plant as set forth in claim 8 in which said flange has a height greater than its radial length and said cylindrical portion has a radial thickness less than the radial length of said flange.
 10. A processing plant as set forth in claim 9 in which each sleeve has a bore extending therethrough of generally uniform diameter. 